I'm a happy user of Workspaces.
I upgraded to Ubuntu 20.04.3 and appear to have broken Workspaces.
I have 2 monitors.
When I click "Activities" or , I enter the Workspaces switcher. I have (only ever) seen one of the screens thumbnailed but I have always (until the upgrade) been able to switch between Workspaces that comprise Windows that span both (2) virtual screens, i.e. when I switch between Workspaces, even though only one screen is thumbnailed, I moved between Workspaces that comprise windows across 2 screens.
Since the upgrade (!?), when I switch Workspaces, one of the windows|screens remains unchanged while the other continues to let me switch between Workspaces.
It as if Workspaces (now understandably) accepts that, because I have 2 actual screens that I may wish to switch Workspaces between each independently.
However, I now (appear to) have no way to switch Workspaces on one of the physical screens.
Ideally I'd like to (return to what I had previously and) have Workspaces treat my 2 physical screens as a single Workspace that comprises 2 virtual screens. Alternatively, I'd like to be able to switch Workspaces on either screen independently.